Apparatus of this type for transferring mass are known from West German Accepted Application (DE-AS) 2,554,062. Therein, the tube sheets, because of the overlapping of the casing openings, have the advantage that sealing surfaces are present between the overlap and the casing opening, which surfaces permit good sealing by bracing the tube sheets against the casing--if necessary by interposing sealing rings. Such a configuration is only possible, however, if the tube sheets are fabricated separately. For installation in the casing, the tubes must be threaded into holes provided in the tube sheet and must be connected to the tube sheet. Thus the fabrication of such apparatus for transferring mass is very expensive.
Apparatus for transferring mass and/or heat are also known in which the tube sheets are fabricated by assembly, a sealing compound in which the tube ends are embedded and which subsequently hardens being cast in the casing openings. Self-curing casting compounds or thermoplastic melts (European Patent A 168,558) are used for this purpose. In this type of fabrication, which is less expensive, tube sheets that overlap the casing openings can indeed also be fabricated, but it has been found that detachment of the casting compound from the casing occurs because of the unavoidable volume decrease of the casting compound during hardening. Sealing by bracing is no longer guaranteed in this type of fabrication, because an uneven tube sheet surface is produced due to the detachment of the tube sheet from the casing. Apparatus for transferring mass and/or heat of the initially mentioned type with a large number of tubes have therefore been regarded as unmakeable in this way.